基于近红外光谱的未知类别样品聚类方法研究

对于大量样品参与建模的情况,将样品集进行分类建模,可以减少样品的变异范围,提高近红外模型的预测能力。本文以全国各地小麦样品222份为建模样品,采用基于试探的未知类别的样品聚类方法,分别用最邻近规则法和最大最小距离算法对实验样品集分类建模。从分类实现过程和结果可以看出：基于试探的未知类别的样品聚类方法中无需多次训练,且对未知类别的样品集无需事先确定分类数目,但需要确定分类阈值,阈值不同,则分类结果会随之改变。     

近红外漫反射光谱技术快速无损识别灵芝和云芝提取物研究

为了满足食用菌提取物实际生产监管需要,本研究采用近红外漫反射光谱技术对来自不同地区的灵芝和云芝提取物样品进行定性识别研究。在800~2 750nm波段范围,采集灵芝和云芝提取物的漫反射光谱,应用主成分聚类分析和偏最小二乘判别法分别建立识别模型,用146个样品进行建模和48个外部样品集进行验证。结果表明:采用主成分聚类判别分析法,灵芝和云芝提取物的判别界线清晰,正确率达到88.54%;采用偏最小二乘判别法,建立的鉴别分类模型能较好地对灵芝和云芝提取物进行鉴别,校正集和预测集样品的识别正确率均为100%。因此,近红外结合主成分聚类分析和偏最小二乘判别法识别灵芝和云芝提取物是可行的,同时研究结果为灵芝和云芝提取物的快速识别提供了理论依据和使用方法。     

二维相关光谱结合偏最小二乘法测定牛奶中的掺杂尿素

为了检验牛奶中是否掺杂尿素并将其量化测定,配置含有尿素质量浓度范围为1～20g/L之间40个牛奶样品,以掺杂物尿素浓度为外扰,分别研究了掺杂尿素牛奶的二维相关(近红外-近红外,中红外-中红外,近红外-中红外)光谱特性,在此基础上,分别选择随浓度变化大的4200～4800cm-1和1400～1704cm-1为建模区间,采用偏最小二乘方法建立定量分析模型。研究结果表明:4200～4800cm-1建模分析效果优于1400～1704cm-1建模结果,其交叉验证均方根误差为0.266g/L,对未知样品集预测相关系数达到0.999,预测均方根误差为0.219g/L,这表明所建模型具有较好的预测效果。该方法无需样品处理,成本低,为快速判别牛奶是否掺杂提供了一种新的可能的方法。     

按批修改法在水保植物研究中的应用

<正> 目前分类中所采用的聚类分析法多为系统聚类法。系统聚类法的基本思路是先将N个样品各自看成一类,然后确定样品或类与类之间的距离,距离最小的两类合并为一个新类;计算新类与其它类的距离,再将距离最近的两类合并。经过如此合并,直至达到要求的距离系数为止。由于距离系数的定义不同,其计算方法也不同。由系统聚类法的思路可知,对于特     

基于最优二叉决策树分类模型的奶牛运动行为识别

针对奶牛行为分类过程中决策树算法构建主观性强、阈值选取无确定规则,易导致分类精度差的问题,该文提出一种基于最优二叉决策树分类模型的奶牛运动行为识别方法,首先选取描述奶牛腿部三轴加速度数值大小、对称性、陡峭程度、变异程度、不确定性及夹角的24个统计特征量,其次通过构建ROC(receiver operating characteristic,ROC)曲线获得各统计特征量的最佳行为类别分组方式及最优阈值,然后利用信息增益作为最优二叉决策树划分属性的选择标准,最终构建最优二叉决策树分类模型对奶牛运动行为进行分类识别。试验结果表明,该分类模型能够有效区分奶牛的站立、平躺、慢走、快走、站立动作、躺卧动作6种运动行为,平均准确率、平均精度、平均F1值分别为76.47%、76.83%、76.57%,相较传统的ID3(iterative dichotomiser 3,ID3)决策树算法分别高5.71、5.4和5.61个百分点,分别高于K-means聚类算法7.51、8.02和7.77个百分点,优于支持向量机算法6.77、6.72和6.57个百分点。该方法可为提高奶牛行为分类精度提供有效的理论支撑。     

基于聚类分析的农业SCADA服务器预警阈值提取方法

针对计算机服务器预警阈值人为设定不准确的问题,该文以某农业数据采集与监视控制系统(supervisory control and data acquisition,SCADA)中Apache服务器为研究对象,提出一种基于聚类分析提取服务器监控指标预警阈值的方法。首先对服务器运行数据与某类异常发生前的预警信息进行特征选择。在数据分布形状未知的情况下,对特征选择结果分别用K-means和CURE(clustering using representative)2种聚类算法挖掘异常发生前服务器运行状态的普遍特征,将聚类结果用于提取该类异常的预警阈值。试验表明:特征选择可提取出影响该SCADA系统中服务器性能的监控指标。对比聚类结果,CURE算法聚类质心与正常信息质心的距离范围为0.02~0.05,而K-means算法聚类质心与正常信息质心的距离范围为0.15~0.2,CURE算法提取的预警阈值更加靠近预警发生时的服务器临界状态。在实际验证中,CURE相较于K-means预警时间至少提前24 h,该文方法提取的服务器预警阈值相比人工方式能更早地发现系统潜在风险,可用于动态更新预警阈值。     

滇青、青饼和普洱茶（熟饼）近红外指纹图谱分析

为深入了解滇青（晒青毛茶）、青饼和普洱茶（熟饼）在化学组成方面的异同,为茶类的区分与界别提供进一步的科学依据,对滇青、青饼和普洱茶（熟饼）的近红外化学指纹图谱采用欧氏距离、主成分分析和系统聚类等方法进行了定性判别分析。结果发现,普洱茶（熟饼）近红外指纹图谱与滇青、青饼图谱间的欧氏距离均大于各自组内最大偏差的绝对阈值,而滇青和青饼的组间差异小于各自的组内阈值;在第一主成分和第二主成分得分值散点图上,熟饼样品与青饼和滇青样品间界限分明,而滇青和青饼样品间无明显界限;所有的熟饼样品在系统聚类分析中聚为一类,而青饼与滇青样品聚为一类。因此,青饼的近红外光谱在各方面都与普洱茶（熟饼）样品差异显著,而与其原料滇青（晒青毛茶）十分接近。从化学本质上来说,青饼更接近于绿茶类产品。     

基于近红外光谱技术的三种硬实种子无损鉴定

摘要：为探讨近红外光谱技术在鉴定种子硬实特性上的普遍性,该文采用近红外光谱法结合偏最小二乘法建立了大豆、苦豆子和决明子单粒种子硬实特性的定性分析模型,每种种子均选择120粒种子进行近红外定性分析,种子分为建模集、检验集2组,建模集80粒,检验集40粒,各组中硬实与非硬实种子的比例为1:1,比较了光谱重复次数、光谱范围以及不同建模样品的建模效果。结果表明：采用二次平均光谱所建模型的鉴别率优于单次光谱;大豆采用4 000～5 000 cm-1光谱范围,矢量校正预处理,主成分为8时,建模集与检验集鉴别率均在85%以上;决明子采用4 000～8 000 cm-1光谱范围,一阶导数预处理,主成分为4时,模型建模集与检验集鉴别率均在90%左右;苦豆子采用4 000～8 000 cm-1光谱范围,二阶导数预处理,主成分为8时,模型的建模集与检验集鉴别率均在95%以上。以上结果表明近红外光谱技术可以很好地应用于单粒种子硬实特性的判断,有助于硬实机理的深入研究。     

中分辨率卫星数据分类的改进迭代聚类算法

在动态聚类算法的理论基础上,提出了一种经过改进的迭代聚类方法。该方法通过VC＋＋程序编译加以实现,在分类的过程中通过判定类间距离阈值动态分类,无需设定初始聚类中心,减少了分类前需要设定的初始参数,保证了分类结果更加客观,并且分类过程简便易操作。为了验证其实用性,本文选取了辽宁中部一区域作为试验区,应用TERRA卫星MOD IS和FY3A卫星MERSI 250m中分辨率数据进行分类,并同时与ISODA-TA法的分类结果进行比较。结果表明,使用该方法得到的分类精度好于ISODATA法,可以用于遥感数据的分类。     

近红外光谱技术定量分析玉米杂交种纯度

摘要：应用近红外光谱分析技术结合定量偏最小二乘法对先玉335杂交种纯度进行了定量分析,将不同年份和来源的杂交种和其母本种子粉碎后混合,按0.5%的梯度获得纯度80～100%范围内的样本123份（每梯度按年份和来源设置3个重复）后采集光谱。结果表明：采用散射校正预处理,4 000～8 000 cm-1光谱范围时建模效果较适宜（建模集∶检验集=3∶1）,建模集内部交叉决定系数达96.06%,校正标准差1.18%,平均相对误差1.03%;检验集的决定系数均达到95.02%,校正标准差1.28%,平均相对误差1.12%。采用不同比例的建模样品和检验样品时,建模集和检验集的决定系数均在94%以上,证明了近红外光谱技术定量测定玉米杂交种纯度的可行性以及所建模型的稳定性。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

Responses of native legume desert trees used for reforestation in the Sonoran Desert to plant growth-promoting microorganisms in screen house

Three slow-growing legume trees used for desert reforestation and urban gardening in the Sonoran Desert of Northwestern Mexico and the Southwestern USA were evaluated whether their growth can be promoted by inoculation with plant growth-promoting bacteria (Azospirillum brasilense and Bacillus pumilus), unidentified arbuscular mycorrhizal (AM) fungi (mainly Glomus sp.), and supplementation with common compost under regular screenhouse cultivation common to these trees in nurseries. Mesquite amargo (Prosopis articulata) and yellow palo verde (Parkinsonia microphylla) had different positive responses to several of the parameters tested while blue palo verde (Parkinsonia florida) did not respond. Survival of all tree species was over 80% and survival of mesquite was almost 100% after 10 months of cultivation. Inoculation with growth-promoting microorganisms induced significant effects on the leaf gas exchange of these trees, measured as transpiration and diffusive resistance, when these trees were cultivated without water restrictions.